Engine Generator Wye-Delta Switching for High Torque Starting
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Solution Overview
Problem
Existing engine generators require costly high current capacity devices to achieve large torque for engine starting, as they need to pass large current through the stator winding to boost drive voltage, increasing operational costs.
Innovation Solution
An engine generator with a three-phase winding that can switch between wye-connection and delta-connection configurations, controlled by an engine speed detection unit, to optimize torque output during engine starting, allowing high torque development without the need for expensive high current capacity devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If large current is passed through the stator winding to boost drive voltage during engine starting, then torque output is improved, but device complexity and cost increase due to requiring high current capacity devices
Solution Approach 1:
The patent applies the dynamics principle by making the winding connection configuration changeable during operation. The connection switching unit dynamically switches between wye-connection and delta-connection based on engine speed detection, allowing the system to adapt its electrical configuration to different operational phases. This dynamic reconfiguration enables high torque output during starting without requiring permanently oversized high current capacity devices, as the system only needs to handle high current temporarily during the starting phase when in wye-connection.
Solution Approach 2:
The patent applies parameter changes by altering the electrical connection configuration parameter of the three-phase winding. By switching between wye-connection (providing higher starting torque) and delta-connection (providing higher running speed), the system changes its electrical parameters to match different operational requirements. This parameter change allows the generator to function effectively as a starter motor without requiring the power converter circuit to be designed for continuously high current capacity, thereby reducing device complexity and cost.
2Force
If high current capacity devices are used in the power converter circuit to achieve large torque, then torque output is improved, but cost increases
Solution Approach 1:
The dynamic switching between wye-connection and delta-connection allows the system to achieve high torque temporarily during starting without requiring permanently oversized components. The power converter circuit only needs to handle high current during the brief starting phase, not continuously, which significantly reduces the required current capacity of the devices and lowers overall system cost.
Solution Approach 2:
The system employs periodic action by using the wye-connection configuration only during the specific periodic phase of engine starting when high torque is needed, then switching to delta-connection for normal operation. This time-based differentiation allows the use of smaller, less expensive components that only need to handle high current during the brief starting period rather than continuously.
3Adaptability or versatility
If the generator is used as an engine starter motor, then versatility is improved, but the power converter circuit requires high current capacity devices increasing complexity
Solution Approach 1:
The patent applies universality by designing the power converter circuit to perform multiple functions: it can convert AC to DC for normal generator operation and also convert DC to AC for engine starting operation. The connection switching unit enables the same circuitry to serve dual purposes by reconfiguring the winding connections, eliminating the need for separate dedicated starting equipment and reducing overall system complexity.
Solution Approach 2:
The dynamic reconfiguration capability allows the single power converter circuit to adapt between different operational modes (generator mode and motor mode). By switching connection configurations based on operational requirements, the system achieves multi-functionality without requiring separate specialized circuits for each function, thereby maintaining relatively simple device architecture despite the versatile capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The engine generator effectively produces high torque for engine starting while minimizing cost by switching to wye-connection initially and then to delta-connection as engine speed increases, maintaining efficient torque output across varying engine speeds without the need for costly power converter components.
Implementation Method 1
a generator unit (2) having a three-phase winding (24) and driven by the engine (1) to generate electric power and configured to be able to operate as an engine starter motor during engine starting
Data Source
AI summary
An engine generator, including an engine having a piston reciprocating inside a cylinder, a generator unit having a three-phase winding, driven by the engine to generate power and operating as an engine starter motor during engine starting, a power converter circuit connected to the generator unit, a battery supplying power to the generator unit through the power converter circuit during engine starting, an engine speed detection unit detecting an engine speed, a connection switching unit switching a connection configuration of the winding to one of a wye-connection and a delta-connection, and a connection switching control unit controlling the connection switching unit to switch the connection configuration to the wye-connection when the engine speed is lower than a predetermined engine speed, and to switch the connection configuration to the delta-connection when the engine speed is equal to or higher than the predetermined engine speed, during engine starting.